Abd El Naser H. El Refae¹, Hany k. shalaby², Sherif Mohamed Abo El Ezz^{3 1} professor of oral medicine and periodontology, Faculty of Dentistry ,suaze canal university ² Assistant professor of oral medicine and periodontology, Faculty of Dentistry ,suaze canal university ³BDS , Faculty of Dentistry , Mansoura university Abstract: Statement of problem: The destructive or damaging aspects of the inflammatory host response that develops in the periodontal tissues as a result of the chronic challenge presented by the subgingival bacterial plaque. Purpose: This study aimed to compare the clinical effects of subgingivally delivered Simvastatin 1.2%, Metformin 1% in prepared biodegradable controlled-release gel as an adjunct to scaling and root planning with scaling and root planning alone in treatment of chronic periodontitis. Materials and methods:Forty five chronic periodontitis patients were divided randomly into three groups. Group I: - (Test group I) included 15 patients who were treated with scaling and root planning (SRP) plus placebo gel. Group II: - (Test group II) included 15 patients who were treated with scaling and root planning (SRP) plus Simvastatin gel. Group III: - (Control group) included 15 patients who were treated with scaling and root planning (SRP) plus Metformin gel. Clinical parameters were assessed before treatment (baseline), and at one, three and six months following the treatment for all groups and periapical radiographs were taken before treatment (baseline) and after six months following the treatment. Results:There were statistically significant reduction in pocket depth, modified sulcus bleeding and gain in clinical attachment level for Group II and Group III compared with Group I. There was statistically significant reduction in IBD (regarding the radiographic analysis) in Simvastatin and Metformin groups compared to placebo group. Conclusion: The use of Simvastatin gel or Metformin gel with scaling and root planning can be considered a new effective way for treating patients with chronic periodontitis.